The invention relates to a disc brake, in particular for a motor vehicle, having a synchronization unit. The invention also relates to a method for installing a wear-compensating readjustment apparatus into disc brakes of said type.
Disc brakes of said type are commonly used in vehicles and certain technical appliances. This is the case in particular in the passenger motor vehicle and commercial (utility) vehicle sector. In the case of the typical structural form of a disc brake, the latter is composed of a brake caliper together with an internal mechanism, of generally two brake pads and of the brake disc. By means of a preferably pneumatically actuated cylinder, the cylinder forces are introduced into the internal mechanism, which is also referred to as application apparatus, and said cylinder forces are boosted by means of an eccentric mechanism, for example a brake rotary lever, and transmitted as an application force via threaded spindles to the brake pads and the brake disc, wherein the wear of the brake disc and the brake pads is compensated by means of the threaded spindles.
The application forces act via both brake pads on the brake disc, the rotational movement of which is decelerated in a manner dependent on the magnitude of the application force. Said deceleration is significantly co-determined by the friction coefficient between the brake disc and brake pad. Since the pads are, in terms of construction, designed as wearing parts and the friction coefficients are dependent on the firmness, said pads are generally softer than the brake disc, that is to say the pads undergo a change in pad thickness over their usage duration; they wear. This change in pad thickness gives rise to the need for a wear-compensating readjustment mechanism to compensate the change and thus set a constant air gap. A constant air gap is required in order to keep the response times of the brake short, to ensure the free movement of the brake disc and to provide a stroke reserve for limit load situations.
An example of a wear-compensating readjustment apparatus is described in DE 10 2004 037 771 A1. Here, a drive rotational movement is transmitted for example from a torque-limiting device via a continuously acting clutch to an adjustment spindle of a pressure plunger. The air gap is in this case set continuously.
In the case of a disc brake with more than one threaded spindle, the drive rotational movement for the wear-compensating readjustment of one threaded spindle is transmitted synchronously to the other threaded spindle(s) by a synchronizer. A synchronizer of said type interacts with corresponding components of the threaded spindles, for example chain and sprockets. There are different proposed solutions for the positioning of the synchronizer, for example on a force-transmitting crossmember, behind the brake rotary lever or outside the brake caliper.
DE 40 34 165 A1 illustrates an example of a disc brake having a synchronizing device.
For the wear-compensating readjustment, it is necessary for a readjustment device to be positioned in the brake caliper. Here, the stop, which acts within the readjustment device, of the transmission mechanism of the readjustment device must remain active. As a result, the readjustment device is positioned, that is to say set, in terms of its angular position in the brake caliper in a manner adapted to the respective components.
In this regard, EP 2 307 753 B1 illustrates an example wherein, after the readjustment device has been correctly positioned, a ball is pressed into a pocket situated in the brake caliper laterally at the readjustment device receptacle. The pocket is positioned such that the ball covers a plate part (head plate) of the readjustment device and deforms said plate part during the pressing-in process. The readjustment device is thereby set and fixed in terms of its angular position in the brake caliper. For reasons relating to the system, the readjustment device can thus be fixed only in terms of its angular position but not in terms of its axial position. Small overlaps (ball diameter approximately 5 mm, of which 1.5 mm overlaps the readjustment device) are technically conceivable. It is considered to be disadvantageous that this fixing can loosen under certain adverse loads (for example intense vibrations in defined directions).
There is a constant demand for simplification and for an increase of the service life of disc brakes, with a simultaneous reduction of costs or at least without an additional increase in costs.
It is therefore the object of the present invention to provide an improved disc brake.
The object is achieved by a disc brake according to embodiments of the invention.
The object is also achieved by a method of installing a synchronizing unit in a brake caliper in accordance with embodiments of the invention.
A disc brake is provided which has a synchronization unit as a preassembled group, which is installed into the brake caliper from a pad slot side. Here, the synchronizer is arranged within the application section of the brake caliper in the region of the bearing arrangements on the bearing wall. This is advantageous because no additional mounting of the synchronizer and associated functional elements from the outside is necessary.
A disc brake according to the invention, preferably actuated by compressed air, in particular for a motor vehicle, comprises a brake caliper which has an application section with an application apparatus, preferably with a brake rotary lever, at least one wear-compensating readjustment apparatus for readjustment for compensating wear of brake pads, and a brake disc with a synchronization unit which comprises a readjustment device, a driver device and a synchronizer, wherein the readjustment device and the driver unit are preferably each inserted into a threaded plunger of a spindle unit and mounted by means of a bearing arrangement on a bearing wall of the application section of the brake caliper. The synchronization unit is installed, as a preassembled group together with the readjustment device and the driver device, into the application section of the brake caliper, wherein the synchronizer is arranged within the application section of the brake caliper in the region of the bearing arrangements on the bearing wall.
There is the further advantage that the synchronizer is arranged outside the application mechanism, that is to say neither on the crossmember nor between the latter and the brake rotary lever, but rather on the inner side of the bearing wall. It is thus possible for the brake rotary lever and the spindle units to be installed and also removed separately from the synchronization unit. This saves time during maintenance and repair work.
A method according to the invention for installing a synchronization unit having a readjustment device and a driver device into a brake caliper of a disc brake as described above has the following method steps:
(S1) Assembling the synchronization unit having the readjustment device and the driver device, wherein a synchronizer with synchronizing wheels is arranged on upper ends of the readjustment device and of the driver device; (S2) inserting the synchronization unit thus assembled into an interior space of an application section of the brake caliper through a brake-disc-side bottom plate flange; and (S3) mounting the readjustment device and the driver device of the synchronization unit thus inserted in a bearing wall of the application section of the brake caliper.
In one embodiment, the bearing arrangement of the readjustment device has a bore in the bearing wall of the application section of the brake caliper and a collar on the bearing wall within the application section of the brake caliper, a support disc on the readjustment device, and a bearing block with a holding section. Simple fixing of the readjustment device in the bearing wall is thus possible.
In a further embodiment, a bearing arrangement of the driver device has a bore in the bearing wall of the application section of the brake caliper and a collar on the bearing wall of the application section of the brake caliper, a support disc on the driver device, and the bearing block with a further holding section. Simple fixing of the driver device in the bearing wall is thus also made possible.
In a yet further embodiment, it is provided that each support disc has, in alternating fashion around its edge, two diametrically oppositely situated circular section edges and two diametrically oppositely situated flattened portions, wherein the flattened portions of a respective support disc run in each case parallel to one another. This yields the advantage that the circular section edges and the flattened portions interchange their positions by means of a simple rotation of the support discs, whereby it is possible, in one position of the support discs, for said support discs, in a first position, to be slid with their flattened portions under the collars, and for said support discs to then be rotated into a second position, whereby the circular section edges then interact with the collars so as to form an axial fixing facility.
For this purpose, it is advantageous if each of the bores is surrounded, on the inner side of the bearing wall, by in each case one collar over an angle of approximately 240°, wherein each collar is equipped with a respective collar edge and a respective collar opening. The collar openings thus advantageously make it possible for the support discs, in the first position, to be slid under the collars through the collar openings, where the support discs are then, in the second position, rotated and each form, together with the collars, an axial fixing facility of the readjustment device and of the driver device.
In a further embodiment, the collar openings are situated opposite one another. This yields the advantage that the readjustment device and the driver device, as a synchronization unit, are moved close together during the insertion into the application section of the brake caliper, in order that the support discs of said readjustment device and driver device can then initially be positioned in the center between the collar openings, from where the readjustment device and the driver device can then be slid under the collars to the left and to the right. This yields a simple assembly process.
In a yet further embodiment, each collar edge of each collar has an internal radius which is smaller than an internal radius of the respectively associated bore. This gives rise to a projecting length of the collar edges for simple interaction with the support discs.
If each collar is equipped with diametrically arranged holding regions in relation to a respective bore central point, the support discs can each be fixed by means of a simple rotation through 90°. Other rotations are self-evidently also possible.
In a yet further embodiment, it is provided that, in an installed state of the synchronization unit, the flattened portions of the support discs of the readjustment device and of the driver device are all arranged parallel to one another, wherein said flattened portions run at right angles to an imaginary connecting line of bore central points of the bores. This simplifies the assembly process.
A further embodiment provides that, in the installed state of the synchronization unit, a bearing block is arranged between the readjuster device and the driver device, wherein the bearing block bears with a longitudinal side against the inner side of the bearing wall, wherein in each case one lateral holding section on a narrow side of the bearing block is in positively locking contact with in each case one flattened portion of each support disc and forms a rotation prevention facility for the support discs. Thus, by means of the bearing block, the rotation prevention facility can be made possible by means of a simple insertion.
In a yet further embodiment, the bearing block, with its longitudinal sides, forms guide sections for the synchronizer, for example a chain. The bearing block thus advantageously permits multiple functions. Furthermore, in a further embodiment, the bearing block advantageously forms a counterbearing for the brake rotary lever.
An additional rotation prevention facility can be realized in that the bearing arrangement of the readjustment device and/or the bearing arrangement of the driver device have in each case one fastening element between the respective support disc and the application section of the brake caliper. The fastening element may for example be a ball which is pressed into recesses, provided for the same, of the associated components support disc and brake caliper, and which gives rise to additional positive locking of said components.
Thus, a disc brake with a synchronization unit is created which can be installed into the application section into the bearing seats of the readjustment device and of the driver device through the bottom plate flange of the brake caliper. The synchronization unit can be introduced jointly as a fully assembled unit of readjustment device and driver device together with the synchronizer, for example the chain, through the bottom plate flange.
The following further advantages are achieved in this way:    (a) Simple and inexpensive synchronization,    (b) Simple assembly,    (c) Modular system for different disc brakes,    (d) The synchronization is fully integrated into the application section of the brake caliper, which is a cast part,    (e) A separate cover unit is not necessary.
In an alternative embodiment, it is provided that the bearing arrangement of the readjustment device has a bore in a bearing wall of the application section of the brake caliper, a bearing disc and a head plate with at least one cylinder segment and with at least one surface segment on the readjustment device. This permits advantageously simple installation and fixing of the readjustment apparatus in the bearing wall. This manner of installation may be used even in the case of disc brakes which have only one spindle unit. Situations are however also contemplated in which the readjustment device is arranged for example between the spindle units.
In a further embodiment, the head plate has a conical fastening section which points toward the interior space of the application section and which is fixedly connected to the bearing disc of the readjustment device, wherein the fastening section is connected, at its outer edge, to a disc section to which the at least one cylinder segment and the at least one surface segment are attached. This is advantageous because, in this way, a conventional bearing disc can be used with only minor enhancements. Components and structural space are thus saved.
A yet further embodiment provides that the at least one cylinder segment extends axially into the bore and is at least partially in positively locking contact with the bore, wherein the at least one surface segment extends radially outward and lies with a supporting surface on a counterpart surface on the inner side of the bearing wall of the application section around the bore. In this way, the functions of axial fixing and centering are advantageously made possible in one component.
If the at least one cylinder segment has at least one fixing section which is connected in positively locking fashion to at least one fastening recess of the bore, an advantageously simple fixing of the readjustment device in the bearing wall is thus formed. The bearing wall in the region of the bore is thus advantageously situated between the at least one surface segment and the at least one fixing section of the head plate. The positively locking connection may be realized for example by calking.
For this purpose, it is advantageous for the at least one fastening recess of the bore to be arranged at that end of the bore which is situated at the outer side of the bearing wall, because in this way, the positively locking connection can be produced easily from the outside owing to easy access.
Thus, a disc brake is provided whose synchronization unit has a readjustment device with a head plate with surface segments and cylinder segments. The synchronization unit or else merely the readjustment device alone can be inserted into the bore, provided for the same, in the bearing wall of the brake caliper and positioned with the planar surface segments of the head plate on counterpart surfaces, provided for the same, in the brake caliper, in this case on the inner side of the bearing wall. Radial positioning is realized by way of the cylinder segments. After the assembly of the remaining components, the correct angular position of the readjustment device is set by cyclic operation of the brake. Thereafter, the cylinder segments are, in fixing sections, pushed by use of a tool into fastening recesses, for example lateral pockets, formed for the purpose in the bore in the bearing wall of the brake caliper. This deformation process gives rise to positive locking, which ensures the fixing of the readjustment device in terms of its angular and axial positions.
The following further advantages are attained:    (a) Simple and inexpensive assembly,    (b) Dismounting is possible only in “destructive” fashion; no re-use of defective components,    (c) Secure fixing of the readjustment device by means of the most intense possible positive locking,    (d) No additional components required.
In another alternative embodiment, the bearing arrangement of the readjustment device has a bore in a bearing wall of the application section of the brake caliper, a support sleeve, a washer and a securing element. This advantageously yields the possibility of simple installation and fixing of the readjustment device in the bearing wall. This manner of installation may be used even in the case of disc brakes which have only one spindle unit. Situations are however also conceivable in which the readjustment device is arranged for example between the spindle units.
For this purpose, an embodiment provides that the support sleeve comprises a support body with a flange and comprises a radial toothing. This yields a compact component.
In a further embodiment, the radial toothing is formed as an external and straight toothing, wherein the teeth thereof extend, parallel to a support sleeve axis, over the outer surface of the support body. The toothing can be produced easily.
A yet further embodiment provides that the washer is formed as a type of ring-shaped disc with a ring body with a central opening, wherein the opening is equipped with an internal toothing which is formed as an internal straight toothing and which corresponds to the radial toothing of the support body of the support sleeve. The washer can be produced inexpensively as a simple punched part.
In a yet further embodiment, in the installed state of the readjustment device, the support sleeve is inserted into the bore such that the support body projects outward from the bearing wall through the bore, wherein a face surface of the flange bears against a supporting surface on the inner side of the bearing wall. This yields a simple assembly process.
It is furthermore provided that the washer is slid onto the support body from the outside, wherein the internal toothing of the washer and the radial toothing of the support sleeve are in engagement, wherein the washer bears against the outer side of the bearing wall and is fixed axially on the support body by means of the securing element.
Furthermore, the washer has at least one fixing section which are connected in positively locking fashion to at least one fixing section on the outer side of the bearing wall. There may also be two diametrically arranged fixing sections on the ring body. This permits simple and rapid fixing to the brake caliper, for example by means of a simple deformation process such as calking.
The following advantages are attained:    (a) Simple and inexpensive assembly,    (b) Secure fixing of the readjuster device by means of the most intense possible positive locking,    (c) No additional components required
In a further embodiment of the method, in the method step (S1) of assembling, support discs are rotated about a respective axis such that flattened portions of the support discs run parallel to an imaginary connecting line of bore central points, wherein the readjuster device and the driver device are initially arranged adjacent to one another such that a spacing of a readjuster axis and a driver axis is smaller than a spacing of the bore central points. An advantageously compact construction for installation is thus made possible.
In a yet further embodiment, in the method step (S2) of inserting, circular section edges, which point toward a respective bore, of the support discs are arranged laterally in front of a respective collar opening of collars of the bores.
A further embodiment provides that, in the method step (S3) of mounting, in a first partial step, the readjuster device and the driver device are slid apart in the direction of the imaginary connecting line of the bore central points to such an extent that the support discs are slid, with the circular section edges, which point toward the respective bore, first, over the respective bore between the respective collar and the bearing wall until said circular section edges come to bear against a respective wall between collar and the bearing wall. This yields a simple assembly process without tools.
In a yet further embodiment, in the method step (S3) of mounting, in a second partial step, the support discs are each rotated through 90° about the readjuster axis and about the driver axis such that each circular section edge of the support discs is arranged between a respective holding region of the associated collar and the bearing wall of the application section of the brake caliper, wherein the synchronizer is tensioned. In this way, axial fixing is made possible by means of a simple 90° rotation.
Furthermore, in one embodiment, it is provided that, in the method step (S3) of mounting, in a third partial step, a bearing block is inserted through the bottom plate flange between the readjuster device and the driver device such that the bearing block bears with a longitudinal side against the bearing wall, tensions the synchronizer further and, with in each case one holding section, makes positively locking contact with a flattened portion of the support discs so as to form a rotation prevention facility for the support discs. This yields a simple and rapid assembly process.
For a further rotation prevention action, balls can then be pressed in between the brake caliper and support discs.
An advantageously simple method is thus realized in which no tools or only simple tools are necessary and which can be performed quickly and reliably.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.